I apologise in advance - I really should know the answer to this Q given I've now had bonsai's of various types for 3-4 years BUT age & poor health etc mess with my brain & I get confused on simple things faster than I like.

So basically I'm wondering how soon can I start feeding given the rollercoaster weather the UK is having just now & I'm up North (Belfast)?

In particular I'm wondering about a couple of newly repotted trees done last month just a week before the first snowstorm (wasn't on the radar at that point!) - one was a 6-yo air layered Wisteria that I'm hugely concerned for as this is the coldest winter it's had to cope with, let alone finding itself suddenly going from a soil pot to a grit cascade one. I know they need time to settle down but just how long can I wait before giving them a bit of a kickstart? The Wisteria is under shelter outside in the hope that the worst of the weather didn't do any damage initially.

Apologies twice over for the rambling post - like I say, meds really do bad things to your brain

Not an expert but I think I have some decent horticultural knowledge. As soon as you see new growth is a good rule of thumb regarding fertilizing. Remember, adding fertilizer is just to supplement the tree not to "feed" the tree. So, if you give it fertilizer as a "kickstart" it can actually do the opposite. Trees need water and oxygen up top and, in the roots, and nothing else. The growing process needs to begin before adding any Salts to your soils.

These salts (fertilizer) will compete for water uptake and can remove water molecules from your roots before they had a chance to recover and supply the tree and foliage again. The important thing is to provide your Wisteria good protection from the weather and also another important factor is making sure your substrate particles are the same size and that oxygen and water are in a good balance.

I am not sure if you separated the air-layer from the parent tree? If you did so, why so early? Second, roots from air-layered trees are filled with sugars, starches and carbs so they are actually much more freeze tolerant than the standard roots of the same tree.

If you provided some protection, which it sounds like you did, it should be okay but you have to wait until you see active growth.

Thanks Thomas - I've had the Wisteria for 3 years now bought as an 3-yo air-layered "bonsai" starter - it has been a good active plant since but I was desperately keen to get it into a proper bonsai pot and only had one chance to get the help I needed to do that last month, so circumstances may have been hugely detrimental to its continued progress but there's time yet before I need to really fear the worst I suppose. I do always bubble wrap all my pots and my yard's fairly sheltered from frost but with hindsight it may have been better to have held off until it had at least started growing and the weather less likely to turn downward as it has. I have another pot grown one that's much younger but as they both tend to start growth within a week of each other it will give me a good idea whether the older one has indeed survived. Having waited for ages to get one I felt would have the best potential for early flowering at a price I could afford at the time I'd hate to lose it now.

But thank you on the "feeding" info as indeed I was thinking of doing it to push growth so needed that reminder on the soil chemistry aspect.